RU2761422C2 - Method and device for end rounding of bristles - Google Patents

Abstract

FIELD: personal care devices.

SUBSTANCE: group of inventions relates to a method and device for end rounding of bristles of a toothbrush section containing a set of bristles. The method includes providing a focused laser beam distributing along a geometric main distribution direction and having a main irradiation point, providing relative movement between the end of each bristle and the main irradiation point of the focused laser beam in such a way that the end of each bristle is moved through the main irradiation point on a trajectory having a main component transverse to the longitudinal length of the bristle. The focused laser beam is directed so that the geometric main distribution direction has a main component transverse to the longitudinal length of the corresponding bristle, the end of which is located at the main irradiation point. Rounding of the end is provided by the focused laser beam heating the end and causing it to partially melt and form a rounded end. The method provides relative movement between the main irradiation point and the toothbrush section along the direction having the main component transverse to the trajectory, thereby sequentially exposing ends of the set of bristles to the focused laser beam, thereby forming a toothbrush section containing bristles with rounded ends. The present disclosure also relates to a device.

EFFECT: possibility to adjust a number of parameters using the installation, such as the laser effect, the degree of focus, the speed of relative movement along the trajectory, independently of each other, without causing any problems for any other part of the bristle or toothbrush section, it is easier to adjust various parameters to get the required amount of heat for ends of bristles, it is easier to adjust parameters to get the required heating profile over time.

15 cl, 11 dwg

Description

Scope of invention

The present invention relates to a method for end rounding the bristles of a brush section, preferably a brush section, related to an interdental brush.

The present invention also relates to an apparatus for end-curving the bristles of a brush section containing a plurality of bristles.

Technical prerequisites for creating an invention

Preferably, the ends of the toothbrush bristles are free of sharp or jagged edges to reduce the risk of unwanted gingival erosion and tooth abrasion.

A number of approaches have been proposed over the years for creating bristle ends without sharp or serrated edges.

EP 0060592 B1, published in 1985, discloses a brush provided with bristles made from an organic thermoplastic synthetic material such as nylon, in particular a toothbrush. The free ends of the bristles, which are sharp and therefore may damage soft surfaces, are rounded off by heat treatment. The ends of the bristles are treated with a laser beam. The document discloses that the ends of the bristles extend downward and that the laser source is located below the ends of the bristles. The brush and heat source are subjected to relative movement and heat treatment occurs under an inert gas atmosphere. It may be noted that this setting depends on precisely focusing the laser at the ends of the bristles to ensure that excess heat is not applied to other parts of the brush.

In the document US 4762373, published in 1988, disclosed a method of rounding the tips of the bristles of toothbrushes under the action of laser radiation, in which the rounding process is carried out in an electrostatic field. This is explained as preventing fusion of the individual bristles as well as the formation of a mushroom-like bristle tip. It can be noted that the provision of an electrostatic field adds difficulty, and the presence of electrostatic fields in a modern highly computerized manufacturing plant is often undesirable. It may be noted that this setting also depends on precisely focusing the laser at the ends of the bristles to ensure that excess heat is not applied to other parts of the brush.

In document US 5007686, published in 1991, a method is disclosed in which controlled melting of the tips of the bristles is achieved by using a pulsed laser beam operating in the kilowatt range and having a pulse duration in the microsecond range. It may be noted that this setting also depends on precisely focusing the laser at the ends of the bristles to ensure that excess heat is not applied to other parts of the brush.

It can also be noted that none of the laser-based methods are useful for so-called interdental brushes.

US Pat. No. 5,015,504, published in 1991, discloses that the ends of the bristles of a brush, such as a toothbrush, are treated with a polysiloxane prepolymer which is then cured. The processed bristles are smooth and have rounded ends.

In the document US 5653628, published in 1997, a device for rounding the ends of plastic bristles on rotationally symmetric round brushes is disclosed, which contains a tool in the form of a rotationally symmetric hollow body with an abrasive inner surface that has an inner contour with at least a cross-section , which is zonally smaller than the cross-section of the circular brush, corresponding to the outer contour of the latter, and there is a relative rotational movement and a reversible relative axial movement between the circular brush and the tool.

Thus, several different methods have been proposed for providing end curvature of the brush bristles. However, as will be seen from the explanation below, there is still room for improvement.

The essence of the invention

An object of the present invention is to provide a new and improved method for the end curvature of bristles. It is also an object to provide a new and improved method that is particularly suitable or at least easily adaptable for the end curvature of the bristles of a brush section associated with an interdental brush.

These objectives are achieved by a method for end-rounding the bristles of a brush section containing a plurality of bristles, the method comprising

providing a focused laser beam propagating along the geometric main direction of propagation and having a main point of irradiation,

providing relative movement between the end of each bristle and the main point of irradiation of the focused laser beam so that the end of each bristle moves through the main point of irradiation on a path having a main component transverse to the longitudinal extension of the bristle, while the focused laser beam is directed so that the geometric main the direction of propagation has a main component transverse to the longitudinal extension of the corresponding bristle, the end of which is located at the main point of irradiation, whereby the rounding of the end is provided by a focused laser beam, which heats the end and causes it to partially melt and form a rounded end,

providing relative movement between the main irradiation point and the brush section along a direction having a main component transverse to the path, thereby sequentially exposing the ends of the plurality of bristles to a focused laser beam, thereby forming a brush section containing bristles with rounded ends.

By directing the focused laser beam so that it has a main component transverse to the longitudinal direction of the corresponding bristle at the main irradiation point and by providing relative movement between the end of the bristle and the main irradiation point so that the end of the bristle moves through the main irradiation point in a path having a main component transverse to the longitudinal extension of the bristle, compared to prior art solutions, it is easier to ensure that each end is exposed to the desired amount of heat and at the desired height of the bristles without risk of affecting other parts of the bristles. With the apparatus of the present invention, for example, it is possible to use a laser beam of relatively high power and quickly move the bristles through the main irradiation point, thereby allowing the process to be accelerated without risk of damaging other parts of the bristles or brush sections. It can be noted that with the apparatus of the present invention, it has become possible to adjust a number of parameters, such as laser effect, degree of focus, speed of relative movement along the path, independently of each other, without causing any problems for any other part of the bristle or brush section. Thus, it is easier to tune various parameters to obtain the desired amount of heat for the ends of the bristles. Moreover, it is easier to tune the parameters to obtain the desired heating profile over time.

It may be noted that the trajectory may have a principal component transverse to the geometric principal direction of propagation. This can be the case, for example, when the section of the interdental brush is rotated about the longitudinal axis of the brush section and the focused laser beam is oriented in accordance with a geometrical main propagation, preferably parallel to the longitudinal axis.

It may be noted that the trajectory may have a baseline component located along the geometric baseline direction of propagation. This can be the case, for example, when the section of the interdental brush is rotated about the longitudinal axis of the section of the brush and the focused laser beam is oriented in accordance with the geometric basic propagation predominantly along the tangential direction.

It may be noted that the relative movement between the main point of irradiation and the brush section according to one embodiment may occur along a direction having a main component transverse to the geometric main direction of propagation and transverse to the path. This can be the case, for example, when the interdental brush section rotates about the longitudinal axis of the brush section and the focused laser beam is oriented in accordance with the geometric principal propagation predominantly along the tangential direction, and the relative movement between the main irradiation point and the brush section is predominantly directed along the longitudinal axis of the brush section.

It can be noted that the relative movement between the main point of irradiation and the brush section according to another embodiment may occur along a direction having the main component located along the geometric main direction of propagation and transverse to the path. This may be the case, for example, when the interdental brush section rotates about the longitudinal axis of the brush section, and the focused laser beam is oriented in accordance with the geometric fundamental propagation predominantly along the tangential direction, and the relative movement between the main point of irradiation and the brush section is directed along the longitudinal direction. the axis of the brush section, for example, is due to the relative movement of the laser and / or the brush section and / or the change in the focal length of the laser.

It may be noted that it is believed that the laser itself may have a focal point that is associated with the laser itself. When a laser is used in the method disclosed in this application, there is a point at which the maximum amount of energy is applied to the bristle. This point at which the maximum amount of energy is applied is designated as the main irradiation point. Preferably, the laser is positioned in the system such that the resulting primary point of irradiation coincides with the focal point of the laser.

It may be noted that the brush section may be a separate brush section, which, for example, contains only the shaft and bristles during the end rounding. Alternatively, the brush section may already be part of a more or less finished brush during the end rounding.

Preferred embodiments are presented in the dependent claims and in the description.

The method may further include end cutting the corresponding bristle with a mechanical cutting tool prior to rounding the end.

Mechanical cutting tools are a proven technology and can, for example, cause a section of an interdental brush to rotate relative to the edge of a knife, such as a razor blade or the like.

The method may further include end-cutting the corresponding bristle with a focused laser beam prior to rounding off the end.

Whereas the method involves the use of a laser for the end curvature, using the same laser or a different laser to cut the ends of the bristles may be convenient as the production equipment and general environment, including, for example, security systems, power supply, control systems, etc. have already been designed with a laser in mind. The use of laser cutting before the end rounding can be, for example, performed by moving the laser along the longitudinal axis of the rotating section of the interdental brush, while the laser is configured to cut off the ends of the bristles, after which the same or another laser moves along the longitudinal axis of the rotating section of the interdental brush, when In this case, the laser in this case is made with the possibility of performing the end curvature of the ends.

The method may further comprise end cutting the corresponding bristle with a focused laser beam while the end is heated to round off. This can be done in a variety of ways. The degree of focus and the maximum intensity can be selected, for example, so that when the interdental brush section is rotated about the longitudinal axis of the brush section and when the focused laser beam is oriented in accordance with the geometric basic propagation predominantly along the tangential direction, the bristle is heated before, during and / or after passing through the main irradiation point to make an end rounding and for the bristle to be cut while passing through the main irradiation point.

The method may further include positioning the brush section in the first fixture and holding the brush section in the first fixture during both end cutting and end rounding of the ends. Thus, it is easier to ensure that the ends are located in a predetermined position when the laser applies heat to the end curvature. It may be noted that the first attachment is intended to mean the attachment actually interacting with and holding the brush section. The first attachment can be moved from the end cut position to the end rounding position, but since the first attachment retains engagement with the brush section, any misalignment of the brush section relative to the attachment in the end rounding position is eliminated. In a preferred embodiment, the first attachment also interacts with and retains the brush section during twisting of the bar to attach the bristles to the bar.

The method can be adapted to end curvature of the bristles of an interdental brush or an interdental brush section, and especially an interdental brush having an interdental brush section that comprises a brush shaft extending along a longitudinal axis and a plurality of bristles supported by the shaft and extending from the shaft in a substantially radial direction. Thus, it can also be assumed that the method includes the step of providing an interdental brush section comprising a brush bar extending along a longitudinal axis and a plurality of bristles supported by the bar and extending from the bar in a substantially radial direction. It may be noted that an end rounding can be performed after the interdental brush has been completed or assembled into an interdental brush, or that an end rounding can be performed on a section of an interdental brush, such as a section of an interdental brush, containing a brush bar extending along the longitudinal axis. and a plurality of bristles supported by a shaft and extending from the shaft in a substantially radial direction before the interdental brush section has been assembled or integrated into other portions to form, together with the interdental brush section, a complete interdental brush.

The method may further include

providing a section of an interdental brush that includes a brush bar extending along a longitudinal axis and a plurality of bristles supported by the bar and extending from the bar in a substantially radial direction,

wherein the step of providing relative movement between the end of each bristle and the main point of irradiation of the focused laser beam includes rotating the brush section about the longitudinal axis so that the end of each bristle passes around the longitudinal axis along a circular path in which the end passes the main point of irradiation along a circular path,

wherein the step of providing relative movement between the main irradiation point and the brush section includes providing relative movement of the main irradiation point along the longitudinal axis, thereby sequentially exposing the ends of the plurality of bristles to a focused laser beam, thereby forming a brush section containing bristles with rounded ends.

Rotating such a section of the interdental brush is a convenient way of giving each bristle a desired path through the primary irradiation point. Moreover, manufacturing devices in use today typically include equipment for rotating the interdental brush section or interdental brush, thereby facilitating implementation.

Moving the irradiation point along the longitudinal axis while rotating the interdental brush section is a convenient way to ensure that each end of the bristle is rounded. The relative movement of the main point of irradiation along the longitudinal axis can be performed in several different ways. The laser itself can be moved. The focused laser beam can be redirected by tilting the laser, or more preferably by tilting the optics or mirror in the laser. The brush or brush section can be moved. Of course, combinations of these methods are also possible. Relative displacement can also be achieved in other ways.

The method may further include directing the focused laser beam so that the geometric main direction of propagation forms an angle of up to about 45 degrees, inclusive, with respect to the tangent line of the circular path at the main irradiation point. It can be noted that the focused laser beam can thus be tilted in any direction with respect to the tangent line, provided that the angle formed between the tangent line and the geometric main direction of propagation is up to approximately 45 °. It can be noted that the main direction of propagation may be along or may be opposite to the tangent line of the trajectory. Thus, the allowable angles can be considered to be within the hourglass double cone, with the cone walls forming an angle of 45 ° with respect to the centerline of the cones. By orienting the focused laser beam in this predominantly tangential direction, it is easy to move the irradiation point along the longitudinal direction. Moreover, the orientation also makes it easy to orient the laser to provide preheating and / or additional heating to the ends of the bristles. Moreover, the orientation also allows end rounding and optionally also end cutting of bristles having different lengths to be easily carried out. The bristles having different lengths can be used to provide a curved profile to the geometric surface of the shell defined by the ends of the bristles.

The method may further include end-cutting the corresponding bristle with the focused laser beam by allowing the focused laser beam to move relative to the longitudinal axis, thereby end-cutting the plurality of bristles prior to allowing the focused laser beam to move relative to the longitudinal axis to round off the ends.

The focused laser beam can have a maximum intensity of 10-20,000 W / mm ² at the geometric focusing point. Intensity is usually reported as a characteristic of the laser itself. In the method, the main irradiation point may refer to a point including the geometric focus point, but which is a point slightly larger than the geometric focus point. The main point of irradiation may, for example, refer to a point having an intensity of at least 90%, preferably at least 95% of the intensity at the geometric focusing point.

The method may further include focusing the focused laser beam onto a primary irradiation point having an area of 0.01 to 1.0 mm ² . Thereby, a well-defined main irradiation area can be obtained.

The method may further include focusing the focused laser beam onto a main irradiation point having a maximum width in a plane transverse to the geometric fundamental direction of propagation that is less than three, preferably less than twice, the width in a direction orthogonal to the maximum width. Thereby, a well-defined main point of irradiation can be obtained. The main point of irradiation can usually be circular when viewed along the focused laser beam.

The method may further include focusing the focused laser beam to a focusing depth of 100 to 10,000 microns. The depth of focus can be defined as the distance measured along the geometric main direction of propagation between two planes on either side of the geometric focus point along the propagation direction at which the intensity per surface area is 95% of the intensity per surface area at the geometric focus point. Thereby, a well-defined main irradiation area can be obtained.

The method may further include exposing the corresponding end of the bristle to a focused laser beam for a period of 100-100000 μs, thereby heating the end and causing it to partially melt. This time interval is considered appropriate to provide sufficient heating at an acceptable rate to achieve the desired partial melting.

The laser can be of any suitable type. This could be, for example, a Nd: YAG laser such as a lamp or diode pumped Nd: YAG laser. This can be, for example, a continuous-wave Nd: YAG laser. This can be, for example, a fiber laser such as an ytterbium fiber laser. This can be, for example, a powerful diode laser. This can be, for example, a CO ₂ laser.

The above objectives have also been achieved with a bristle end-rounding device for a brush section containing a plurality of bristles, the device comprising:

a laser containing a laser beam source and optics configured to provide a focused laser beam propagating along a geometric main direction of propagation and having a main point of irradiation,

a device for holding a brush section containing a plurality of bristles, wherein the device is configured to provide relative movement between the end of each bristle and the main point of irradiation of the focused laser beam so that the end of each bristle moves through the focused laser beam at the main point of irradiation in a trajectory having main component transverse to the longitudinal extension of the bristle,

whereby the focused laser beam is directed so that the geometric main direction of propagation has a main component transverse to the longitudinal extension of the corresponding bristle, the end of which is located at the main point of irradiation, whereby the rounding of the end is ensured by the focused laser beam, which heats the end and causes it to partially melt and form the rounded end, and

wherein the device is configured to provide relative movement between the main irradiation point and the brush section along a direction having a main component transverse to the trajectory, thereby sequentially exposing the ends of a plurality of bristles to a focused laser beam, thereby forming a brush section containing bristles with rounded ends ...

By directing the focused laser beam so that it has a main component transverse to the longitudinal direction of the corresponding bristle at the main irradiation point and by providing relative movement between the end of the bristle and the main irradiation point so that the end of the bristle moves through the main irradiation point in a path having a main component transverse to the longitudinal extension of the bristle, compared to prior art solutions, it is easier to ensure that each end is exposed to the desired amount of heat and at the desired height of the bristles without risk of affecting other parts of the bristles. With the apparatus of the present invention, for example, it is possible to use a laser beam of relatively high power and quickly move the bristles through the main irradiation point, thereby allowing the process to be accelerated without risk of damaging other parts of the bristles or brush sections. It can be noted that with the apparatus of the present invention, it has become possible to adjust a number of parameters, such as laser effect, degree of focus, speed of relative movement along the path, independently of each other, without causing any problems for any other part of the bristle or brush section. Thus, it is easier to tune various parameters to obtain the desired amount of heat for the ends of the bristles. Moreover, it is easier to tune the parameters to obtain the desired heating profile over time.

It may be noted that the trajectory may have a principal component transverse to the geometric principal direction of propagation. This can be the case, for example, when the section of the interdental brush is rotated about the longitudinal axis of the brush section and the focused laser beam is oriented in accordance with a geometrical main propagation, preferably parallel to the longitudinal axis.

It may be noted that the trajectory may have a baseline component located along the geometric baseline direction of propagation. This can be the case, for example, when the section of the interdental brush is rotated about the longitudinal axis of the section of the brush and the focused laser beam is oriented in accordance with the geometric basic propagation predominantly along the tangential direction.

It may be noted that the relative movement between the main point of irradiation and the brush section according to one embodiment may occur along a direction having a main component transverse to the geometric main direction of propagation and transverse to the path. This can be the case, for example, when the interdental brush section rotates about the longitudinal axis of the brush section and the focused laser beam is oriented in accordance with the geometric principal propagation predominantly along the tangential direction, and the relative movement between the main irradiation point and the brush section is predominantly directed along the longitudinal axis of the brush section.

It can be noted that the relative movement between the main point of irradiation and the brush section according to another embodiment may occur along a direction having the main component located along the geometric main direction of propagation and transverse to the path. This may be the case, for example, when the interdental brush section rotates about the longitudinal axis of the brush section, and the focused laser beam is oriented in accordance with the geometric fundamental propagation predominantly along the tangential direction, and the relative movement between the main point of irradiation and the brush section is directed along the longitudinal direction. the axis of the brush section, for example, is due to the relative movement of the laser and / or the brush section and / or the change in the focal length of the laser.

The device can be configured to rotate the brush section about the longitudinal axis so that the end of each bristle extends around the longitudinal axis in a circular path.

The laser may be oriented with respect to the fixture such that the focused laser beam is directed towards the bristles of the brush section in the fixture so that the end of the corresponding bristle, passing along a circular path, passes the main point of irradiation.

The device can be configured to provide relative movement between the tool and the main irradiation point along the longitudinal axis such that the laser beam is sequentially directed towards the corresponding end of the plurality of bristles.

The features of the different embodiments of the method are equally applicable to different embodiments of the apparatus.

The method and / or apparatus may further comprise a focused laser beam directed at an angle relative to a tangent line such that more energy from the laser beam is applied to the bristle before the bristle reaches the main point of irradiation, compared to the amount of energy applied to the bristle. after the bristle has passed the main point of irradiation. This can be referred to as preheating the ends of the bristles.

The method and / or apparatus may further comprise a focused laser beam directed at an angle relative to a tangent line such that less energy from the laser beam is applied to the bristle before the bristle reaches the main point of irradiation, compared to the amount of energy applied to the bristle. after the bristle has passed the main point of irradiation. This may be referred to as reheating the ends of the bristles.

Brief Description of Drawings

The present invention, by way of example, will be described in more detail with reference to the accompanying schematic drawings showing a presently preferred embodiment of the present invention.

FIG. 1a is a top view of an interdental brush.

FIG. 1b is a top view of an interdental brush according to another embodiment in which the ends of the bristles are of different lengths so that the geometric circular surface of the shell has a curved profile along the longitudinal direction.

FIG. 1c is a top view of a brush section.

FIG. 2 is a side view of a laser irradiating the end of a bristle.

FIG. 3 is an enlarged view of FIG. 2.

FIG. 4 is a second side view of the apparatus of FIG. 2.

FIG. 5 is a top view of a device comprising the apparatus of FIG. 2-4.

FIG. 6 shows an installation providing additional heating.

FIG. 7 shows a preheating unit.

FIG. 8 is a schematic diagram of a method for end rounding of the bristles of a brush section.

FIG. 9 is a schematic representation of a bristle with rounded ends.

Detailed Description of Preferred Embodiments

The method and device for the end rounding of the bristles are specially designed for the end rounding of the bristles of the brush section related to the interdental brush.

FIG. 1a and FIG. 1b shows a typical interdental brush 1 according to the first and second embodiments. The interdental brush 1 comprises a handle 2 from which a brush shaft 3 extends along a longitudinal axis L. The brush shaft 3 may be formed from a twisted metal wire, which is preferably coated with a protective polymer coating. The brush shaft 3 supports a plurality of bristles 4. The corresponding bristle 4 extends from the shaft mainly in the radial direction R. It can also be said that the elongated bristles 4 extend with their longitudinal extension LE in the radial direction R. The shaft 3 extends into the interior of the handle 2 and is attached to the handle 2 This is indicated by a dashed line extending from the visible part of the rod 3 into the handle 2. The attachment can, for example, be done with the rod 3 clamped between the two halves of the handle 2, or with the handle 2, cast with the rod 3 inserted into the cavity for casting, forming a handle 2. The rod 3 with bristles 4 may be referred to as a brush section 1 'as shown in FIG. 1c. The rod 3 can be twisted along its entire length only along the distance over which it supports the bristles 4, or it can, as shown in FIG. 1c, be twisted by a distance slightly exceeding the distance of the part that supports the bristles 4, and further the last innermost part of the rod 3 is not twisted, but the strands of the rod 3 run parallel to each other.

The ends of the setae 4 are rounded. This corresponds to a preferred embodiment carried out by a method which, in short, with reference to FIG. 8 is thought to include

providing 110 brush sections such as an interdental brush section,

attachment 120 of the brush section 1 ', such as in the first tool 21,

rotation of 130 brush sections,

end cutting of 140 bristles,

the end rounding of 150 ends of the bristles, and

displacement 160 of the main point of irradiation of the laser 10 along the longitudinal direction L.

It may be noted that it is preferable that the end rounding is performed on the brush section 1 ', mainly formed from the rod 3 and the bristles 4. However, the method is equally applicable to the finished brush 1 or to any intermediate state between the brush section 1' formed from a rod 3 and bristles 4, and a finished brush 1.

The end rounding is performed using a focused laser beam 11 propagating along the geometric main propagation direction PD and having a main irradiation point 12 as shown in FIG. 2 and in the enlarged view of FIG. 3.

Rotation 130 of the brush section 1 'about the longitudinal axis L provides relative movement between the end of each bristle 4 and the main irradiation point 12 of the focused laser beam 11. Rotation 130 causes the end of each bristle 4 to travel around the longitudinal axis L along a circular path P, while along a circular path P, the end passes through the main point 12 of irradiation. It may be noted that this causes the end of each bristle 4 to move through the main irradiation point 12 on a path P having a main component transverse to the longitudinal extension LE of the bristle 4.

As shown in FIG. 2 and 3, the focused laser beam 11 is directed such that the geometric main propagation direction PD has a main component transverse to the longitudinal extension LE of the corresponding bristle 4, the end of which is located at the main irradiation point 12. In the embodiment shown in FIG. 2 and 3, the geometric main propagation direction PD is orthogonal to the longitudinal extension LE of the corresponding bristle 4, the end of which is located at the main irradiation point 12. FIG. 6 and 7, the focused laser beam 11 is oriented with its geometrical main direction PD of propagation at different angles, which is not orthogonal, but still has a main component transverse to the longitudinal extension LE of the corresponding bristle 4, the end of which is located at the main irradiation point 12. The end rounding 150 is provided by a focused laser beam 11 heating the end and causing it to partially melt and form a round end.

As shown in FIG. 4, the focused laser beam 11 is configured to move 160 of the main irradiation point 12 along the longitudinal axis L of the brush section 1 ', thereby allowing relative movement between the main irradiation point 12 and the brush section 1' and thereby sequentially exposing the ends of the plurality of bristles 4 to the focused laser beam 4. It can be noted that the focused laser beam 11 is directed so that it does not hit the top of the brush section, but instead flies past the brush section with the main irradiation point 12 located in the plane in front of the brush section 1 'or in the plane behind brush section 1 ', as shown, for example, in FIG. 2. Once the sequence 160 is complete, a brush section 1 'is provided containing bristles 4 with rounded ends. It can be noted that the relative movement 160 between the main irradiation point 12 and the brush section 1 'occurs in a direction having a main component transverse to the path P. In the illustrated embodiment, the relative movement 160 is orthogonal to the path P.

According to one embodiment, the method further comprises end cutting 140 of the corresponding bristle 4 by means of a mechanical cutting tool 40 before rounding 150 the end of the corresponding bristle 4. This cutting can, for example, be performed by rotating the brush section 1 'about the longitudinal direction L with the bristles 4, extending against the edge 40 of a knife, such as a razor blade 40. This is shown in FIG. 5. The edge of the knife can, for example, move between an active position, where it cuts the bristles (shown in solid lines), and an inactive position (shown in dashed lines). After the bristles 4 have been trimmed with the cutting tool 40, the laser 10 is activated and the end curvature 150 occurs on the bristles 4.

In accordance with one embodiment, the method includes end cutting 140 of the corresponding bristle 4 by means of a focused laser beam 11 before rounding 150 of the end. This can be done, for example, with a separate laser. However, if the end cut is performed using a laser, it is currently preferred that the method includes using the same laser 10 for end cut 140 and end rounding 150, whereby relative movement of the focused laser beam 11 along the longitudinal axis L is also provided for an end-cutting operation 140 such that the plurality of bristles 4 are trimmed before relative movement of the focused laser beam 11 along the longitudinal axis L is achieved to round off the ends of the bristles 4. This may, for example, be done by passing all the way along all of the bristles 4 for operation 140 end cut, followed by a complete pass along all of the bristles 4 for step 150 end rounding. Alternatively, the end cut 140 and the end rounding 150 can be divided into parts such that first the ends of the bristles 4 of the first part are cut 140 and round off 150, located along a part of the longitudinal axis, and then the ends of the bristles 4 of the second part are cut 140 and round off 150. ... Such a stepwise process can, for example, be useful if the relative movement is provided as a combination of redirecting the focused laser beam 11 and translational movement.

In accordance with one embodiment, the method further comprises end cutting 140 of the respective bristle 4 by means of a focused laser beam 11, while the end is heated to round off 150. This can be done, for example, using a laser 10 to both cut 140 the end and to round off 150 the end of the corresponding bristle 4. These simultaneous end cut 140 and end round 150 are indicated by dashed brackets in FIG. eight.

As shown in FIG. 5, the method further includes positioning the brush section 1 'in a first tool 21 comprising a first portion 21a and a second portion 21b, and holding the brush section 1' in a first tool 21a, 21b during both end cutting 140 and end curvature 150 of the corresponding bristles 4. This fixture 21 with its portions 21a, 21b is also used to perform the twisting of the rod 3. Part 21a of the fixture captures two strands of the rod 3 and part 21b of the fixture captures the folded end. The relative rotation of the parts 21a and 21b of the fixture causes the part of the rod 3 to twist between the parts 21a, 21b of the fixture.

However, it may be noted that, alternatively, the brush section 1 'can be gripped by the first tool 21 during end cutting and then transferred to another tool 21 holding the brush section 1' in place during the end rounding 150.

FIG. 2 and 3, the main direction of propagation PD of the focused laser beam 11 is directed so that it is parallel to the tangent line P 'of the circular path P at the main irradiation point 12, but in the opposite direction from it. FIG. 4 shows how the angle of the main propagation direction PD changes from a first angle α1, which is slightly less than 45 ° on the first side, to a second angle α2, which is slightly less than 45 °, on the second side of the tangent line P 'of the trajectory P, the angles being measured between the tangent line P 'of the path P at the principal irradiation point 12 and the main direction of propagation PD. It may be noted that in FIG. 4, the angle α is used to ensure the passage of the focused laser beam 11. It is also possible that the laser beam 11 is provided at a fixed angle α, and that the brush section 1 'and / or the laser source 10 move along the longitudinal axis L. It is also possible to use a combination of the passage of the focused laser beam 11 as shown in FIG. 2, and relative translational movement. The angle α is measured in a plane defined by the longitudinal axis L and the tangent line P 'of the circular path P at the main irradiation point 12.

FIG. 6 and 7 show how the main direction of propagation PD of the focused laser beam 11 is directed so that it forms an angle β in a defined circular path P relative to the tangent line P 'of the circular path P at the main irradiation point 12. FIG. 6 and 7, the plane defined by the circular path P is parallel to the plane of the paper. Both β1 and β2 are less than 45 ° and preferably less than 30 °.

It can be noted that the focused laser beam 11 can be tilted, as described above, both at an angle α and at an angle β. One or both corners can be fixed and / or one or both corners can be actively changed during the end rounding.

It may be noted that it is also possible that the focused laser beam 11 can be directed such that the main propagation direction PD and the tangent line P 'of the circular path P at the main irradiation point 12 are directed in the same direction.

Thus, it is preferred that the focused laser beam 11 is directed relative to the tangent line P 'of the circular path P at the main irradiation point 12 substantially within the hourglass-shaped double cone, with the lateral surfaces forming an angle of up to 45 ° with respect to the center line formed the tangent line P 'of the circular path P at the main point 12 of irradiation.

The focused laser beam 11 has a maximum intensity of 10-20,000 W / mm ² at the geometric focusing point.

The focused laser beam 11 has a focus point having an area of 0.01 to 1 mm ² .

The focused laser beam 11 preferably has a circular focal point or focal point at least having a maximum width that is less than 2 times the width in a direction orthogonal to the maximum width.

The focused laser beam 11 has a wavelength of 300 to 11000 nm.

The focused laser beam 11 has a focusing depth of 100 to 10,000 μm. Focusing depth, defined as the distance measured along the direction of propagation between two points 12 'and 12' 'on either side of the geometric focus point along the direction of propagation, where at points 12', 12 '' the intensity per surface area is 95% of the intensity on the surface area at the geometric focus point. FIG. 3 shows a focusing point 12 "" with alternative geometries. The focal point 12 "" has a maximum width w1, which is slightly less than twice the minimum width w2.

When the end rounding is performed, the corresponding end of the bristle is exposed to a focused laser beam for a period of 100 to 100,000 μs, preferably 100 to 10,000 μs, thereby heating the end and causing it to partially melt. This can, for example, be done by rotating the bristle section 1 'about a longitudinal axis at a rotational speed of about 100 to about 10,000 rpm, with the main irradiation point 12 being a distance R of about 0.5 mm to 10 mm from the axis L rotation, thereby imparting to the end of the bristle 4 a tangential velocity of 0.01 to 10 m / s along the tangent line P 'of the trajectory P.

It can be noted that when the focused laser beam 11 is directed with respect to the tangent line P 'and with respect to the direction of rotation, as shown in FIG. 6, less energy from the laser beam 11 is applied to the bristle 4 before the bristle 4 reaches the main irradiation point 12, compared to the amount of energy applied to the bristle 4 after the bristle 4 has passed the main irradiation point 12. This may be referred to as reheating the ends of the bristles.

It can be noted that when the focused laser beam 11 is directed with respect to the tangent line P 'and with respect to the direction of rotation, as shown in FIG. 7, more energy from the laser beam 11 is applied to the bristle 4 before the bristle 4 reaches the main irradiation point 12, compared to the amount of energy applied to the bristle 4 after the bristle 4 has passed the main irradiation point 12. This can be referred to as preheating the ends of the bristles.

FIG. 9 schematically shows a bristle 4 with an end that is rounded in accordance with the method and apparatus disclosed above.

As noted in FIG. 9, the end curvature generally results in a teardrop shape at the end of the bristle 4. The teardrop shape of the rounded end has a maximum elongation D along the radial direction of the bristle extending a distance of 1.1 to 2 times, preferably 1.1 to 1.5 times than the maximum elongation d of the unaffected portion of the bristle 4. The unaffected portion of the bristle 4 generally has a circular cross-section, and the maximum elongation is generally the diameter d. The teardrop shape is usually circular in cross section and the maximum elongation is mainly D.

The teardrop shape of the rounded end has an elongation H along the longitudinal elongation LE, with the bristle 4 being 1.1-2 times, preferably 1.1-1.5 times, the maximum elongation d of the unaffected part of the bristle 4.

The bristles 4 are preferably made of polyamide or polyester. The corresponding bristle 4 preferably has a diameter of about 0.03 to 0.2 mm.

It is contemplated that there are many modifications of the embodiments described herein, which are still within the scope of the invention as defined by the appended claims.

Claims (28)

1. A method for end rounding of bristles of a brush section (1 ') containing a plurality of bristles (4), the method comprising providing a focused laser beam (11) propagating along the geometric main direction (PD) of propagation and having a main point (12) of irradiation, providing relative movement between the end of each bristle (4) and the main point (12) of irradiation of the focused laser beam (11) so that the end of each bristle (4) moves through the main point (12) of irradiation on the trajectory (P) having the main component transverse to the longitudinal elongation (LE) of the bristle (4), while the focused laser beam (11) is directed so that the geometric main direction (PD) of propagation has a main component transverse to the longitudinal elongation (LE) of the corresponding bristle (4), the end which is located at the main point (12) of irradiation, whereby the rounding of the end is provided by a focused laser beam (11), which heats the end and causes it to partially melt and form a rounded end, providing relative movement between the main point (12) of irradiation and the section (1 ') of the brush along the direction (L) having a main component transverse to the path (P), thereby sequentially exposing the ends of the plurality of bristles (4) to a focused laser beam (11 ), thereby forming a brush section (1 ') containing bristles (4) with rounded ends. 2. A method according to claim 1, further comprising end cutting the corresponding bristle (4) by means of a mechanical cutting tool (40) prior to rounding off the end. 3. A method according to claim 1, further comprising end-cutting the corresponding bristle (4) by means of a focused laser beam (11) before rounding the end. 4. A method according to claim 1, further comprising end-cutting the respective bristle (4) by means of a focused laser beam (11) while the end is heated to round off. 5. The method according to any one of claims. 2-4, characterized in that it further comprises positioning the brush section (1 ') in the first tool (21) and holding the brush section (1') in the first tool (21) during both end cutting and end rounding of the ends. 6. A method according to any one of the preceding claims, characterized in that the brush section is an interdental brush section (1 '), the method further comprising providing a section (1 ') of an interdental brush, which comprises a brush bar (3) extending along the longitudinal axis (L) and a plurality of bristles (4) supported by the bar (3) and extending from the bar (3) in a predominantly radial direction (R ), the step of providing relative movement between the end of each bristle (4) and the main point (12) of irradiation of the focused laser beam (11) includes rotation of the section (1 ') of the interdental brush around the longitudinal axis (L) so that the end of each bristle (4 ) passed around the longitudinal axis (L), as a result of which the trajectory (P) along which the end of each bristle (4) moves through the main point (12) of irradiation becomes a circular trajectory (P), in which the end passes the main point (12) irradiation along a circular path (P), wherein the step of providing relative movement between the main point (12) of irradiation and the section (1 ') of the brush includes providing relative movement of the main point (12) of irradiation along the longitudinal axis (L), thereby sequentially exposing the ends of the plurality of bristles (4) to the action of a focused laser beam (11), thereby forming a section (1 ') of the brush, containing bristles (4) with rounded ends. 7. The method according to claim 6, further comprising directing the focused laser beam (11) so that the geometric main direction (PD) of propagation forms an angle (α, β) of up to 45 ° with respect to the tangent line (P ') circular trajectory (P) at the main point (12) of irradiation. 8. A method according to claim 6 or 7, characterized in that it further comprises end cutting the corresponding bristle (4) by means of a focused laser beam (11) by providing relative movement of the focused laser beam (11) along the longitudinal axis (L), thereby end-cutting the plurality of bristles (4) before allowing the focused laser beam (11) to move relative to the longitudinal axis (L) to round off the ends. 9. A method according to any of the preceding claims, characterized in that the focused laser beam (11) has a maximum intensity of 10-20,000 W / mm ² at the geometric focusing point (12). 10. A method according to any of the preceding claims, characterized in that it further comprises focusing the focused laser beam (11) onto a geometric focusing point (12) having an area of 0.01 to 1.0 mm ² . 11. The method according to any of the previous claims, characterized in that it further comprises focusing the focused laser beam on the geometric focusing point (12) having a maximum width (w1) that is less than twice the width (w2) in a direction orthogonal to the maximum width (w1). 12. A method according to any of the preceding claims, further comprising focusing the focused laser beam (11) to a focusing depth (fd) of 100 to 10,000 μm. 13. A method according to any of the preceding claims, further comprising subjecting the respective end of the bristle to a focused laser beam (11) for a period of 100-100000 μs, thereby heating the end and causing it to partially melt. 14. A device for end rounding of the bristles of a brush section containing a plurality of bristles, the device comprising: a laser (10) comprising a laser beam source and optics configured to provide a focused laser beam (11) propagating along a geometric main direction (PD) of propagation and having a main point of irradiation (12), a device (21) for holding the brush section (1 ') containing a plurality of bristles (4), while the device (21) is configured to provide relative movement between the end of each bristle (4) and the main point (12) of irradiation of the focused laser beam ( 11) so that the end of each bristle (4) moves through the focused laser beam (11) at the main point (12) of irradiation in a path (P) having a main component transverse to the longitudinal elongation (LE) of the bristle (4), the focused laser beam (11) is directed so that the geometric main direction (PD) of propagation has a main component transverse to the longitudinal elongation (LE) of the corresponding bristle (4), the end of which is located at the main point (12) of irradiation, whereby the rounding the end is provided by a focused laser beam (11), which heats the end and causes it to partially melt and form a rounded end, while the device is configured to provide relative movement between the main point (12) of irradiation and the section (1 ') of the brush along the direction (L) having a main component transverse to the trajectory (P), thereby sequentially exposing the ends of the plurality of bristles (4) exposure to a focused laser beam (11), thereby forming a brush section (1 ') containing bristles (4) with rounded ends. 15. The device according to claim 14, characterized in that the device (21) is configured to rotate the brush section (1 ') around the longitudinal axis (L) so that the end of each bristle (4) runs around the longitudinal axis (L) along a circular path (P), the laser (10) is oriented relative to the device (21) so that the focused laser beam (11) becomes directed towards the bristles (4) of the section (1 ') of the brush in the device (21) so that the end of the corresponding bristle (4), passing along a circular path (P), passed the main point (12) of irradiation, and the device is configured to provide relative movement between the device (21) and the main point (12) of irradiation along the longitudinal axis (L) so that the focused laser beam (11) becomes sequentially directed towards the corresponding end of the plurality of bristles (4).

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